Process of manufacturing steel.



No. 843,592. PATENTED FEB. 12, 1907.

Y B. E. ELDRED. PROCESS OF MANUFACTURING STEEL.

APPLIOATION FILED MAY 20, 1905.

WITNESSES: INVENTOR rn'rnN'r orat on. I

nNrrnn sta ns BYRON E.-ELDRED, OF NEW YORK, N. Y., AssIeNOR TO COMBUSTION UTILI- TIES COMPANY, OF NEW YORK, N. Y., A CORPORATION OF EW YORK.

PROCESS OF MANUFACTURING STEEL.

Specification of Letters Patent.

Patented Feb. 12, 1907.

Application filed May 20. 1905. Serial No. 261,442.

To all whom it may concern:

Be it known that I, BYRON E. ELDRED, a

citizen of the United States, and a resident of.

New York city, inthe county of'New York and State of New York,- have invented certain new and useful Improvements in Proc-- esses of Manufacturing Steel, of which the following is a specification.

This invention relates to a process for the ess. In the manufacture of steel by the atter method many difficulties have arisen, due to the impossibility of properly controlling the temperature of the molten mass. In blowing the converter with an air-draft the temperature of the steel will often rise to an extremely high point, giving rise to reactions which are injurious to the metal and misleading to the operator. ess the object is generally to burn olffirst silicon and then carbon. The oxidation of the former is productive of a very high temperature, owing to the fact that no gaseous products of combustion accompany this reaction and the gas escaping is small. The gas evolved is chiefly nitrogen from the air-blast. The heat loss as sensible heat is in consequence less than that occurring in the second stage of oxidation in which the carbon is burned, during which stage the volume of gas is much greater and the sensible heat losses are of far greater moment. It is in connection with the first stage of oxidation or silicon slagging stage that this process particularly concerns itself. As above stated, the oxidation should ordinarily proceed successively from silicon to carbon; but this sequence of oxidation occurs only when the temperature is held sufficiently low. It has been found that when the temperature rises above a certain critical point the oxygen of the blast shows aseleotive action or aflinity for the carbon and burns the carbon out of the steel before the silicon is well oxidized. Reactions of this sort cause the production of oor material and often of steel containing a igh content of silicon. They are furthermore misleading to the operator. Steam has been used in the past ,to some extent as a temperaturecontrolling agent; but because of its oxidizing action on the steel, its high cost of genera- In the Bessemer proc-' tion, its high specific heat, &c., it has been found a most unsatisfactory agent for. temperature control.

Atvthe'high temperatures as reached in the manner above described, the nitrogen of the air-blast has been found to have. a deleteiri ous action on the steel. Nitrogen combines to a certain extent with the metal to form nitrids. Another portion is undoubtedly occluded, and this occluded portioncannot be removed, as is the case with oxygen by ferromanganese or spiegeleisen.

' The object of this inventionis to provide a means for temperature control in steel manna facture, which will eliminate the troubles due to the reversal of the order of the combustion of silicon and carbon, will prevent the formation of nitrids, largely reduce the amount of occluded gases, andin addition will have no deleterious action on the steelas regards oxidation or otherwise.

My invention consists in keeping the temperature in the converter during the; oxidation of the silicon at a point below the critical temperature, at which preferential oxide-.- tion of the carbon begins by theintroduction of a regulated draft-current containing an endothermically-acting agent.

Referring to the accompanying diagrammatic drawings, 1 shows a section of a converter of the conventional form having-the trunnions 2, the air-chest 3, the twyers 4-, theconnectingair-pipe 5, trunnion air-inlet 6.

i 7 is an air-supply with the air-reservoir 8. I

9 is a furnace having the grate 10, hearth 11, and stack 12.

At 13 is an outlet for the products of combustion through the passage or conduit 14. This conduit leads to the filter 15, Where carbon in the solid form, tar, dust, &c., are removed. Interposed in this conduit is thepipe having connection spectively, provide a means for the regulation-- D l of the amount of air and-productsof'oom bustion or of oxygen andcarbon dioxid enteringthe filter 15.

19 is an air-pump having the inlet 2ft) from the filter and the outlet. 21, leading: to the reservoir at 24. v

22 and 23 are steam inlets and outlets, respectively.

' The operation of the process with the apparatus asdescribed is as follows: The prod ucts. of combustion of the furnace 9 ordinarily passing up the U stack as waste gases are drawn wholly or in part through the conduit 14 and filt'er15 by the air-compressor 19.

At the same time air is admitted throu h the inlet 16.; This mixture isforced into t e reservoir 8-, from which it may be permitted to enter the; converter 1. The converter havin previously been filled with molten iron t e blas'twill pass therethrough and oxidize-the impurities. At the start of this operation a pure air blast'may be used, if desired; but asthe temperature rises, due to the oxidation of silicon, the damper 17 should be gradually opened to allow of the introduction of carbon dioxid or products of combustion along with the air. The introduction of carbon dioxid results in. a pronounced cooling action on the metal, and the guantity needed toprevent the temperatureomrising to the critical reversal point may.

' be determined by observation of the flame,

"ratus, kind of steel required, 850. 'It is not where coke-gills inecessary'inthe practice of my process to inject this gaseous mixture at the bottom only ofithe converter. -It-may also be introduced at the sides or to thereof, or through certain of the tiyyers the blast containing carbon dio'xid be introduced, while throughl others a pure-air blast may be injected. some instances the filter may be dispensed with, especially inthose furnace operations producers and the like are employed w 'ch afford products of combustion containing little or no soot or-dust. The air-inlet 16 has been diagrammatically indicated as in the inlet'li. It may be also 10- catedin the passage 20, and this in some cases is preferable, as it permits of the use of asmaller filter. l Products, of combustionmay, be derived fromany' suitable source, such as heating furnaces of j'v-arious sorts or from calcining and?the like, which often afford prpdfilgducts of ordinary combustion. From aucts of combustion containing a greater per centage of carbon dioxid than that present in ekiln, for instance, the proportion of nitrogen low'and that of carbon dioxid high by virtue of the gaseous products" of decomposition of the calcareous material.

. It is possible "also to withdraw products of combustion fi'oin the converter itself, al though these at certain stages of the blow xhibit so great a paucity of carbon dioxid 0d of. operation may be varied to that reliance must be had chiefly upon the I nitrogen, which largely constitutes the gas at this stage of the operation, 'A- reduction in temperature at thisperiod by the use of nitrogen is to some degree possible; but the injection of nitrogen reduces the temperature of the converter only through the deportation of sensible heat, whereas carbon dioxid under similar circumstances is split up, its constituents entering into other combina tions by reactions which are endothermic in character, so that the introduction of carbon 'dioxid is much more effective for kee ing down the temperature in the converter t an if it merely acted by the deportation of sensible heat, as does nitrogen.

In the conduit 14 a cooling a paratus may be placed provided the'gases fr nace 11 are too hot to be handled safely by the air-com ressor. The conduit 14 often has to be 0 considerable length, in which case the radiation therefrom may prove sufiicient to secure the desired reductlon of tenlperature.

Otherwise an apparatus having a ositive cooling action or inserted in the conduit 14. When the gases of combustion are obtainedfrom a steamboiler furnace, they have, owing to their transit through the boiler-fines, been subject-s ed to g a, cooling action sufficient to enable their being handled in the com ressor without danger. The addition of co (1 air through the air-inlet on the suction side of the compressor also reduces the temperature of the gases entering the compressor.

By the use of this process advantages of great commercial importance are obtained. The possibility of controlling the temperature of the converter'by means of a non-oxidizing agent which is ordinarily a waste product and without cost is of great commercial significance. The use of carbon dioxid in thls manner solves the troubles heretofore experienced in accomplishing a roper consecutive and rapidremoval of s' ca and carbon.

The carbon dioxid or the products of com-' bustion in this rfipect appear to have a catating in an accelerationv of sions than those heretofore employed.

My process for the manufacture of steel enables the production of a metal resembling o en-hearth steel at' a cost very much less t an the latter. It therefore enables me to substitute Bessemer steel for o en-hearth steel in many of those large fie ds ofconsumption from which Bessemer steel has heretofore been debarred, owing to its brittleness and lack of strength.

om the furarily should bego Having now described my invention and shown in what manner it may be practiced and in what respect important advantages are secured over those obtaining in the present practice of this art, I claim and desire to secure by Letters Patent 1. The method of preventing premature oxidation of carbon during the making of steel by the pneumatic or Bessemer process, which consists in maintaining the-temperature during the oxidation of the silicon at a point below the critical point at which seective oxidation of carbon in preference to silicon begins, by introducing a diluting nonoxidizing endothermic agent into the draftcurrent in the proportion necessary to maintain such temperature.

2. The method of preventing premature oxidation of carbon during the making of steel by the pneumatic or Bessemer process, which consists in maintaining the temperature during the oxidation of the silicon at a oint below the critical point at Which seective oxidation of carbon in preference to silicon begins, by introducing carbon dioxid into the draftcurrent in the proportion necessary to maintain such temperature.

3. The method of preventing premature oxidation of carbon during the making of steel by the pneumatic or Bessemer process, which consists in maintaining the temperature during the oxidation of the silicon at a point below the critical point at which selective oxidation of carbon in preference to silicon begins, by introducing furnace-gases into the draft-current in the proportion necessary to maintain such temperature.

4. The method of reventing premature oxidation of carbon dhring the making of steel by the pneumatic or Bessemer process, which consists in maintaining the temperature during the oxidation of the silicon at a oint below the critical point at which seective oxidation of carbon in preference to silicon begins, by introducing cooled furnace: gases into the draft-current in the proportion necessary to maintain such temperature.

5. The process of controlling the temperature in a Bessemer blow which consists in continuously admixing with the air-blast varying amounts of a diluting endothermic gas, said amounts being proportioned to the'ob served tendency of the Bessemerized metal to rise in temperature above a desired point.

6. The rocess of controlling the temperature in a essemer blow which consists in diluting the air-draft used with progressivelyincreasing amounts of an endothermic gas.

7. The process of controlling the temperature in a Bessemer blow which consists 11]. diluting the air-draft used with progressivelyincreasing amounts of products of combus' tion.

Signed at New York city, in the county of New York and State of New York, this 17th day of May, A. D. 1905.

BYRON E. ELDRED. Witnesses:

CARLETON ELLIS, A. M. SENIOR. 

